5042-7493 - flow & burn mark

Breaking Force Analysis Report

for 5042-7293 Vcsel Lower

Housing Black (FL)

Burn mark defects

Burn mark

Flow mark

Defects highlight:

Defects List: Burn mark Flow mark

Defects Quantity: 800 pcs in Hi-Optel 50kpcs in Enplas warehouse

Root Cause Investigation

Enplas checked in-house stock and found all condition are same as picture below.

Flow MarkFlow line formed at points or areas where divergent flows of molten resin meet inside the cavity.Note:{{Avago define flow mark would not affected the part functionality, so part is safe to use}}

Burn markWhile the molten resin flows crowed to bursting point inside the cavities and gas cannot be released/escape from gas venting points will gets transformed into something similar to charcoal on the surface of a molded part we called it welding mark.Note:{{Avago worry for the burn mark will weaken the part strength, request for Breaking force reference test}}

Explanation on defects formation:

Breaking test on burn mark area refer to normal sample

Conducted breaking test

Enplas conduct a breaking force test to check weather burn mark will weaken the part strength.

Normal (Reference) sample

Burn mark sample

Null Hypothesis H0: All the break force groups have equal stress on the average

Breaking test work instruction

Placed properly the “L” rib of part to be tested

Set “zero”

Operate the push gauge down until the rib broken

Left(L) Rib


Set “zero”

Placed properly on “R” rib of part to be tested


Right(R) rib

Operate the push gauge down until the rib broken

Breaking test data analysis

2.500 2.700 2.900 3.100 3.300 3.500 3.700

Reference

Burn

Breaking Force in KgF

Test

Sam

ple

s

The Breaking Force of Burn Mark spot reference with normal part in KgF

The median gap value between 2 sets samples breaking force are small (0.65% differences).

Reference Difference

Min 2.900 2.900

Q1 3.025 0.125

Median 3.060 0.035

Q3 3.240 0.180

Max 3.520 0.280

Burn Difference

Min 2.720 2.720

Q1 2.920 0.200

Median 3.080 0.160

Q3 3.200 0.120

Max 3.380 0.180

Normal Boxplot Burn BoxplotNo. Reference (L/F) Burn (L/F)

1 3.20 2.982 3.04 2.803 3.52 2.724 3.04 3.385 3.36 3.126 3.02 2.987 3.04 3.208 3.24 3.369 2.90 3.32

10 3.24 2.7811 3.02 3.0212 3.02 3.0013 3.30 3.2014 3.06 3.2615 3.06 3.0416 3.04 3.2017 3.08 3.2618 3.52 3.2019 3.44 3.0220 3.06 3.0221 2.90 2.9022 3.08 2.9023 3.26 3.1624 2.92 2.8825 2.94 3.3626 3.04 2.7627 2.98 2.7228 3.28 3.2029 3.10 3.2030 3.04 3.14

Mean 3.1247 3.0693Mode 3.0400 3.2000

Standard 0.1726 0.1980

Raw data

Differences of breaking force between

burn mark sample & normal sample

Total model samples is n=30, Reference sample is μ =3.1247kgF; Burn mark sample is μ =3.0693kgF,

Difference gap: 0.055kgF (1.77%) Small differences.

P value = 0.253338 > 0.05;

Result: Not Significant different between 2 sample mean values.

H0 hypothesis accepted.

Conclusion: The burn mark samples have no significant difference with normal samples breaking force. Therefore, burn mark is appearance defects but not affected part function.

The Request of Concession1. Part surface is not inspected for cosmetic attributes

and this surface of bottom housing will not explore after assembly into mother’s body.

2. Burn mark wouldn’t further lead to any functional issue. Based on breaking test analysis, the burn mark area P-value is 0.253338 > 0.05 which strengthen is no significant different from normal samples. The confident level for the test is 95%.

3. Raw material is expensive and lead time of purchase new material is more than six months.

4. Mold have improved in Enplas Vietnam and FAI sample is submitted to Avago for approval.

5042-7493 - flow & burn mark

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